[PATCH 15/33] target/mips: Add emulation of MXU D32ADD instruction

[Siarhei Volkau]

The instruction adds/subtracts two 32-bit values in XRb and XRc.
Placing results in XRa and XRd and updates carry bits for each
path in the MXU control register.

Signed-off-by: Siarhei Volkau <lis8215@gmail.com>
---
 target/mips/tcg/mxu_translate.c | 64 +++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

diff --git a/target/mips/tcg/mxu_translate.c b/target/mips/tcg/mxu_translate.c
index 5596d86234..03be624d86 100644
--- a/target/mips/tcg/mxu_translate.c
+++ b/target/mips/tcg/mxu_translate.c
@@ -378,6 +378,7 @@ enum {
     OPC_MXU__POOL09  = 0x15,
     OPC_MXU__POOL10  = 0x16,
     OPC_MXU__POOL11  = 0x17,
+    OPC_MXU_D32ADD   = 0x18,
     OPC_MXU_S8LDD    = 0x22,
     OPC_MXU__POOL16  = 0x27,
     OPC_MXU__POOL17  = 0x28,
@@ -2249,6 +2250,66 @@ static void gen_mxu_q16add(DisasContext *ctx)
     tcg_gen_or_tl(mxu_gpr[XRd - 1], t0, t1);
 }
 
+/*
+ * D32ADD XRa, XRb, XRc, XRd, aptn2 - Double
+ * 32 bit pattern addition/subtraction.
+ */
+static void gen_mxu_d32add(DisasContext *ctx)
+{
+    uint32_t aptn2, pad, XRc, XRb, XRa, XRd;
+
+    aptn2 = extract32(ctx->opcode, 24, 2);
+    pad   = extract32(ctx->opcode, 22, 2);
+    XRd   = extract32(ctx->opcode, 18, 4);
+    XRc   = extract32(ctx->opcode, 14, 4);
+    XRb   = extract32(ctx->opcode, 10, 4);
+    XRa   = extract32(ctx->opcode,  6, 4);
+
+    TCGv t0 = tcg_temp_new();
+    TCGv t1 = tcg_temp_new();
+    TCGv t2 = tcg_temp_new();
+    TCGv carry = tcg_temp_new();
+    TCGv cr = tcg_temp_new();
+
+    if (unlikely(pad != 0)) {
+        /* opcode padding incorrect -> do nothing */
+    } else if (unlikely(XRa == 0 && XRd == 0)) {
+        /* destinations are zero register -> do nothing */
+    } else {
+        /* common case */
+        gen_load_mxu_gpr(t0, XRb);
+        gen_load_mxu_gpr(t1, XRc);
+        gen_load_mxu_cr(cr);
+        if (XRa != 0) {
+            if (aptn2 & 2) {
+                tcg_gen_sub_i32(t2, t0, t1);
+                tcg_gen_setcond_tl(TCG_COND_GTU, carry, t0, t1);
+            } else {
+                tcg_gen_add_i32(t2, t0, t1);
+                tcg_gen_setcond_tl(TCG_COND_GTU, carry, t0, t2);
+            }
+            tcg_gen_andi_tl(cr, cr, 0x7fffffff);
+            tcg_gen_shli_tl(carry, carry, 31);
+            tcg_gen_or_tl(cr, cr, carry);
+            gen_store_mxu_gpr(t2, XRa);
+        }
+        if (XRd != 0) {
+            if (aptn2 & 1) {
+                tcg_gen_sub_i32(t2, t0, t1);
+                tcg_gen_setcond_tl(TCG_COND_GTU, carry, t0, t1);
+            } else {
+                tcg_gen_add_i32(t2, t0, t1);
+                tcg_gen_setcond_tl(TCG_COND_GTU, carry, t0, t2);
+            }
+            tcg_gen_andi_tl(cr, cr, 0xbfffffff);
+            tcg_gen_shli_tl(carry, carry, 30);
+            tcg_gen_or_tl(cr, cr, carry);
+            gen_store_mxu_gpr(t2, XRd);
+        }
+        gen_store_mxu_cr(cr);
+    }
+}
+
 /*
  *                 MXU instruction category: Miscellaneous
  *                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -3033,6 +3094,9 @@ bool decode_ase_mxu(DisasContext *ctx, uint32_t insn)
         case OPC_MXU__POOL11:
             decode_opc_mxu__pool11(ctx);
             break;
+        case OPC_MXU_D32ADD:
+            gen_mxu_d32add(ctx);
+            break;
         case OPC_MXU_S8LDD:
             gen_mxu_s8ldd(ctx);
             break;
-- 
2.40.0